Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751699AbdF2W27 (ORCPT ); Thu, 29 Jun 2017 18:28:59 -0400 Received: from mail-yw0-f172.google.com ([209.85.161.172]:36738 "EHLO mail-yw0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751554AbdF2W24 (ORCPT ); Thu, 29 Jun 2017 18:28:56 -0400 MIME-Version: 1.0 In-Reply-To: References: <149875877608.10031.17813337234536358002.stgit@dwillia2-desk3.amr.corp.intel.com> <149875884190.10031.6179599135820559644.stgit@dwillia2-desk3.amr.corp.intel.com> <595552F5.5040008@hpe.com> <59556E37.80808@hpe.com> From: Dan Williams Date: Thu, 29 Jun 2017 15:28:55 -0700 Message-ID: Subject: Re: [PATCH v4 12/16] libnvdimm, nfit: enable support for volatile ranges To: Linda Knippers Cc: "linux-nvdimm@lists.01.org" , Jan Kara , Matthew Wilcox , X86 ML , "linux-kernel@vger.kernel.org" , Al Viro , linux-fsdevel , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 960 Lines: 19 On Thu, Jun 29, 2017 at 3:12 PM, Linda Knippers wrote: [..] >> The /dev/pmem >> device name just tells you that your block device is hosted by a >> driver that knows how to handle persistent memory constraints, but any >> other details about the nature of the address range need to come from >> other sources of information, and potentially information sources that >> the kernel does not know about. > > > I'm asking about the other source of information in this specific case > where we're exposing pmem devices that will never ever be persistent. > Before we add these devices, I think we should be able to tell the user > how they can know the properties of the underlying device. The only way I can think to indicate this is with a platform + device whitelist in a tool like ndctl. Where the tool says "yes, these xyz-vendor DIMMs on this abc-vendor platform with this 123-version BIOS" is a known good persistent configuration.